EP0265272A2
Expired / Lapsed
EP
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Direct synthesis modem
Assignee: Nortel Networks Ltd
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Filing: 1987-10-22
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Granted: —
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Expires: 2007-10-22
Abstract
Abstract A communication system for connecting a telephone switching office (28) to a data processing center (12) is described. A telephone trunk line (40) from the switching office carries data which is digitally encoded and may be in a compressed format, for example mu-law PCM, and which is derived from remote data terminals (10). A novel type of modem (44) is connected between the trunk and the data processing center. This is a direct synthesis device which converts the modulated digital data directly to a non-modulated digital format readable by the data processing center and, for digital data originating at the data processing center, produces modulated digital data which is transmitted along the trunk to the switching office. The direct synthesis modem is a single, purely digital device which replaces many separate digital/analog modems which are required in conventional systems.
Inventors
- 👤 Jan Heymen
- 👤 Larry S. Kayser
- 👤 George E. Mony
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-27 21:58
CPC Classifications
H; H04; H04M; H04M11/00; H04M11/06; H04L; H04L27/00; H04L27/0008
Claims Analysis
Total Claims: 26
Claim 1
Independent Claim
77 words
A method of transferring data which is in a digitally encoded modulated format and carried on a telephone trunk to a processing center and vice versa comprising directly synthesizing, from the digitally encoded modulated data on the trunk, digital data signals in a non-modulated format readable by the processing center and directly synthesizing, from non-modulated digital data signals output from the processing center, data which is digitally encoded in a modulated format for transmission on the trunk.
Claim 2
Independent Claim
77 words
A method of transferring data which is in a digitally encoded modulated format and carried on a telephone trunk to a processing center and vice versa comprising directly synthesizing, from the digitally encoded modulated data on the trunk, digital data signals in a non-modulated format readable by the processing center and directly synthesizing, from non-modulated digital data signals output from the processing center, data which is digitally encoded in a modulated format for transmission on the trunk.
Claim 3
Dependent Claim
21 words
A method according to claim 1 in which the modulated data on the trunk is in the form of PCM signals.
Claim 4
Dependent Claim
22 words
A method according to claim 1 in which the modulated data on the trunk is in the form of mu-law PCM signals.
Claim 5
Dependent Claim
22 words
A method according to claim 1 in which the modulated data on the trunk is in the form of A-law PCM signals.
Claim 6
Dependent Claim
104 words
A communication system for connecting a telephone switching office to a processing center comprising a telephone trunk capable of carrying data which is digitally encoded in a modulated format and which is derived from a plurality of remote data terminals, and a modem connected between the trunk and the processing center, the modem being arranged to synthesize directly from the digitally encoded modulated data on the trunk, digital data signals in a non-modulated format readable by the processing center and to synthesize directly, from non-modulated digital signals output from the processing center, digital signals encoded in a modulated format for transmission on the trunk.
Claim 7
Dependent Claim
104 words
A communication system for connecting a telephone switching office to a processing center comprising a telephone trunk capable of carrying data which is digitally encoded in a modulated format and which is derived from a plurality of remote data terminals, and a modem connected between the trunk and the processing center, the modem being arranged to synthesize directly from the digitally encoded modulated data on the trunk, digital data signals in a non-modulated format readable by the processing center and to synthesize directly, from non-modulated digital signals output from the processing center, digital signals encoded in a modulated format for transmission on the trunk.
Claim 8
Dependent Claim
89 words
A communication system for connecting a telephone switching office to a processing center comprising a telephone trunk capable of carrying in a plurality of channels PCM signals derived from a plurality of respective remote data terminals and a modem connected between the trunk and the processing center, the modem being arranged to synthesize directly, from the PCM signals on the trunk, digital data signals readable by the processing center and to synthesize directly, from digital data signals output from the processing center, PCM signals for transmission on the trunk.
Claim 9
Dependent Claim
89 words
A communication system for connecting a telephone switching office to a processing center comprising a telephone trunk capable of carrying in a plurality of channels PCM signals derived from a plurality of respective remote data terminals and a modem connected between the trunk and the processing center, the modem being arranged to synthesize directly, from the PCM signals on the trunk, digital data signals readable by the processing center and to synthesize directly, from digital data signals output from the processing center, PCM signals for transmission on the trunk.
Claim 10
Dependent Claim
92 words
A communication system for connecting a telephone switching office to a processing center comprising a telephone trunk capable of carrying in a plurality of channels, mu-law PCM signals derived from a plurality of respective remote data terminals and a modem connected between the trunk and the processing center, the modem being arranged to synthesize directly, from the mu-law PCM signals on the trunk, digital data signals readable by the processing center and to synthesize directly, from digital data signals output from the processing center, mu-law PCM signals for transmission on the trunk.
Claim 11
Dependent Claim
92 words
A communication system for connecting a telephone switching office to a processing center comprising a telephone trunk capable of carrying in a plurality of channels, mu-law PCM signals derived from a plurality of respective remote data terminals and a modem connected between the trunk and the processing center, the modem being arranged to synthesize directly, from the mu-law PCM signals on the trunk, digital data signals readable by the processing center and to synthesize directly, from digital data signals output from the processing center, mu-law PCM signals for transmission on the trunk.
Claim 12
Dependent Claim
92 words
A communication system for connecting a telephone switching office to a processing center comprising a telephone trunk capable of carrying in a plurality of channels, A-law PCM signals derived from a plurality of respective remote data terminals and a modem connected between the trunk and the processing center, the modem being arranged to synthesize directly, from the A-law PCM signals on the trunk, digital data signals readable by the processing center and to synthesize directly, from digital data signals output from the processing center, A-law PCM signals for transmission on the trunk.
Claim 13
Dependent Claim
92 words
A communication system for connecting a telephone switching office to a processing center comprising a telephone trunk capable of carrying in a plurality of channels, A-law PCM signals derived from a plurality of respective remote data terminals and a modem connected between the trunk and the processing center, the modem being arranged to synthesize directly, from the A-law PCM signals on the trunk, digital data signals readable by the processing center and to synthesize directly, from digital data signals output from the processing center, A-law PCM signals for transmission on the trunk.
Claim 14
Independent Claim
71 words
A method of transferring data from a plurality of digital terminal equipments to a processing centre comprising converting digital signals output from the digital terminal equipments to analog signals in respective analog modems, converting the analog signals to digitally encoded modulated signals, passing the digitally encoded modulated signals along a trunk between switching offices, and directly synthesizing, from the digitally encoded modulated signals, non-modulated digital signals readable by the processing centre.
Claim 15
Independent Claim
71 words
A method of transferring data from a plurality of digital terminal equipments to a processing centre comprising converting digital signals output from the digital terminal equipments to analog signals in respective analog modems, converting the analog signals to digitally encoded modulated signals, passing the digitally encoded modulated signals along a trunk between switching offices, and directly synthesizing, from the digitally encoded modulated signals, non-modulated digital signals readable by the processing centre.
Claim 16
Independent Claim
78 words
A method of transferring data from a processing centre to a plurality of digital terminal equipments connected to respective analog modems comprising directly synthesizing, from digital signals output from the processing centre, digitally encoded modulated signals, passing the digitally encoded modulated signals along a trunk between two switching offices, converting the digitally encoded modulated signals to analog signals, and converting the analog signals by means of the analog modems to digital signals readable by the digital terminal equipments.
Claim 17
Independent Claim
78 words
A method of transferring data from a processing centre to a plurality of digital terminal equipments connected to respective analog modems comprising directly synthesizing, from digital signals output from the processing centre, digitally encoded modulated signals, passing the digitally encoded modulated signals along a trunk between two switching offices, converting the digitally encoded modulated signals to analog signals, and converting the analog signals by means of the analog modems to digital signals readable by the digital terminal equipments.
Claim 18
Dependent Claim
27 words
A method of transferring data in both directions between digital terminal equipments and a processing centre comprising carrying out the steps of claim 9 and claim 10.
Claim 19
Independent Claim
36 words
A method of transferring data in both directions between digital terminal equipments and a processing centre, comprising carrying out the steps of claims 9 and 10 and wherein the digitally encoded modulated signals are PCM signals.
Claim 20
Independent Claim
37 words
A method of transferring data in both directions between digital terminal equipments and a processing centre, comprising carrying out the steps of claims 9 and 10 and wherein the digitally encoded modulated signals are mu-law PCM signals.
Claim 21
Independent Claim
37 words
A method of transferring data in both directions between digital terminal equipments and a processing centre, comprising carrying out the steps of claims 9 and 10 and wherein the digitally encoded modulated signals are A-law PCM signals.
Claim 22
Dependent Claim
168 words
A communication system for connecting a plurality of digital terminal equipments to a processing centre comprising a plurality of analog modems connected respectively between the digital terminal equipments and a first telephone switching office, means at the first telephone switching office for converting analog signals from the analog modems to digitally encoded modulated signals and vice versa, first transmission means for carrying digitally encoded modulated signals between the first telephone switching office and a second telephone switching office, second transmission means for carrying digitally encoded modulated signals in both directions between the second telephone switching office and a direct synthesis modem which is connected in turn to the processing centre, the direct synthesis modem being arranged to synthesize directly, from the digitally encoded modulated signals on the second transmission means, non-modulated digital signals readable by the processing centre and to synthesize directly, from non-modulated digital signals output from the processing centre, digitally encoded modulated signals for transmission on the second transmission means and subsequently the first transmission means.
Claim 23
Dependent Claim
168 words
A communication system for connecting a plurality of digital terminal equipments to a processing centre comprising a plurality of analog modems connected respectively between the digital terminal equipments and a first telephone switching office, means at the first telephone switching office for converting analog signals from the analog modems to digitally encoded modulated signals and vice versa, first transmission means for carrying digitally encoded modulated signals between the first telephone switching office and a second telephone switching office, second transmission means for carrying digitally encoded modulated signals in both directions between the second telephone switching office and a direct synthesis modem which is connected in turn to the processing centre, the direct synthesis modem being arranged to synthesize directly, from the digitally encoded modulated signals on the second transmission means, non-modulated digital signals readable by the processing centre and to synthesize directly, from non-modulated digital signals output from the processing centre, digitally encoded modulated signals for transmission on the second transmission means and subsequently the first transmission means.
Claim 24
Dependent Claim
16 words
A communication system according to claim 15 wherein the digitally encoded modulated signals are PCM signals.
Claim 25
Dependent Claim
17 words
A communication system according to claim 15 wherein the digitally encoded modulated signals are mu-law PCM signals.
Claim 26
Dependent Claim
17 words
A communication system according to claim 15 wherein the digitally encoded modulated signals are A-law PCM signals.
References Cited (Backward Citations)
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